1. Technical Field
This description generally relates to the field of electronic devices and, more particularly, to user interfaces of electronic devices.
2. Description of the Related Art
Electronic devices often require entry of data in the form of words, sentences, letters, numbers, characters and symbols by a user in order to perform their designed functions. A typical character entry interface that meets this requirement provides a plurality of buttons, each sized to be easily pressed by a human fingertip, with one character assigned to each button and one button for each character that a user could want to select. In English-language cultures, the QWERTY keyboard is one such standard interface and this interface is commonly found on typewriters and computers.
Some electronic devices, either by design or due to a constraint, do not use the standard interface. Portable electronic devices are an example of an entire category of electronic devices that do not typically provide a standard character entry interface. Users of portable devices typically demand that the device fit easily in a pocket or purse. To meet this requirement, portable devices cannot at the same time offer finger-sized keys and enough keys for all the letters of an alphabet. As many portable devices have functions that require character entry, this leads to a conflict between providing a user interface that offers complete and convenient functionality but in a size that can still be carried inside a user's pocket. Many alternative methods for solving this conflict exist in the prior art, as will be discussed below.
In FIG. 1 a cellular phone is shown having a character entry interface and method known in the prior art. The interface includes twelve physical buttons in a 3×4 matrix on a front face of the phone. Ten of the twelve buttons are assigned a numeral, one numeral per button. Eight buttons are also assigned text characters, three characters per button. Both the numerical and text character assignments are indicated on the face of the button. Characters are selected by first choosing a mode—numeral or text character—that identifies which category of character becomes entered by pressing the button. Within text mode, the particular character entered of the three displayed on a given button face is differentiated by the number of times the button is pressed during a given period.
For example, in FIG. 1 the button in the top row middle column of the interface is assigned the numeral 2 and the text characters a, b, and c. According to the method, while in text mode a user presses the button one time to indicate the character a for selection. To indicate character b for selection, the user presses the button two consecutive times. Similarly, the user presses the button three consecutive times to indicate character c for selection. Sequences of characters that can form words and sentences are indicated by consecutively pressing the appropriate physical button the appropriate number of button presses for each subsequent character in the desired word or sentence. This interface and method are well-known in the art and has the advantage of being compact in size; however, the method has the disadvantage of being slow compared with a standard interface due to the number of button presses required to enter many of the text characters.
In FIG. 2 a character entry interface and method similar to the one shown in FIG. 1 is shown. The method is essentially identical to the one shown in FIG. 1. The interface is different in that the buttons are soft keys, meaning that the buttons are graphically represented on changeable display, rather than physical buttons. An advantage of this interface is that it is configurable, because the graphical representation of the keys can be changed on the display. Therefore, the assignment of characters to buttons, the arrangement of the keys, and the overall size of the interface are variable. The method, however, still has the disadvantage of being slow compared with a standard interface due to the number of button presses needed to enter many of the text characters.
In FIG. 3 another user interface and text entry method known in the art is shown. This interface has thirty keys distributed among three rows, ten keys per row. This interface provides enough buttons that every character of a typical alphabet has its own key. Numeric characters still share keys with a text character, therefore a selection between numeric and text mode is still required. The method of indicating characters for selection is straightforward in that a character is indicated by simply pressing the button that displays the desired character on the button face. This method offers the advantage of faster text entry speeds because multiple character presses are not needed to select any of the characters. A disadvantage of the interface is that to meet size constraints the buttons are small relative to a typical user's fingertip. This leads to slower and less accurate character entry compared with a standard interface.
In FIG. 4 a character entry interface and method similar to the one shown in FIG. 3 is shown. The method is essentially identical to the one shown in FIG. 3. The interface is different in that the buttons are soft keys, rather than physical buttons. Like the interface of FIG. 3, this interface provides enough buttons that every character of a typical alphabet has its own key. Characters are indicated for selection by simply pressing the soft key that displays the desired character. An advantage of this interface over the one of FIG. 3 is that panels of various keys can be exchanged, for example the displayed panel of text characters can be exchanged for a panel of numeric characters. While this interface offers improved configurability over the interface of FIG. 3, the disadvantages of that interface, such as the small buttons relative to the size of a user's fingertips, still exist. A further disadvantage of this interface, and one shared with the interface of FIG. 2, is that soft keys provide no tactile feel to the user. A user cannot tactilely distinguish if their finger is on a key or between keys, therefore this interface requires that a user either visually align their finger with the desired button or verify that the desired character was selected by visually checking a display.
In FIG. 5 a variation on the interface of FIG. 4 is shown. The method of FIG. 5 is essentially identical to the ones shown in FIGS. 3 and 4, however the interface rearranges the buttons, and the assignments of the text characters to the buttons, so that the most frequently used characters of a language are assigned next to one another and close to the center of the interface. For example, the commonly used characters of a, e, s, t, r, and o are assigned to buttons at the center of the interface. On the other hand, the less frequently characters of z, k, x, and q are placed at the corners. This arrangement speeds up character entry by minimizing the time required for a user to move fingers between keys because the most frequently used keys are located close to one another. This improvement highlights one disadvantage that all the character entry interfaces share in common—one or two-finger character entry compared with eight-finger entry on a standard QWERTY interface.
In FIG. 6 yet another character entry interface and method known in the art is shown. This interface uses a stylus and a touch-sensitive display screen. A user traces out shapes or symbols that represent characters directly on the display screen. The electronic device is equipped to interpret and recognize the shapes and associate each unique shape with a different text or numerical character. Shapes traced out on the display screen are interpreted as separate characters based on when the stylus is lifted off on and then placed back on the display screen. Typically the user may trace character shapes out anywhere on the display screen and as long as the electronic device is in a mode to receive and interpret these shapes, the shape will be interpreted and the indicated character understood. As an example, a user may have a note-taking application opened and shown on the display of their electronic device. A user places the tip of the stylus on the display and, if they desire to enter the character a, traces a first line segment diagonally upward and to the right on the display screen, followed by a second line segment straight downward on the screen from the end of the first line segment. Once the user picks the stylus up off the screen, the device seeks to interpret the shape, associate it with a particular character, and if recognizable, enter the indicated character a in the note-taking application. A character is interpreted for each continuous stroke of the stylus along the display screen. This interface has an advantage in that no display of a selection character or buttons is required at all, however the method has the disadvantages of requiring the user to trace out characters rather than pressing buttons and to learn the shapes that associated with each character.
In FIG. 7 still another character entry interface and method known in the art is shown. This interface includes a two-stage display, a first stage that displays all the characters available for selection and a second stage that displays a portion of the first stage in a zoom-in view. In the first stage, the available characters are displayed in a single row. A frame lies over the displayed characters and surrounds a portion of the characters. Whatever characters are within the frame are displayed in the second stage, except of a size much larger than displayed in the first frame. The frame is moveable along the row of characters and as characters enter or leave the frame by its movement, the characters shown in the second stage also correspondingly change. The second frame also includes selection buttons on which the characters in the frame are shown. A user indicates a character for selection by pressing the selection button displaying the desired character. If the desired character is not displayed, the user slides the frame in the first stage to cause the desired character to be shown in the second frame, and then presses the appropriate button to indicate the character for selection. An advantage of the interface is that the selection buttons can be made large because there are selection buttons for only a few characters at any one time. The large buttons make the method highly accurate, but a disadvantage is that two different operations must be conducted per character indicated: first moving the frame along the row of characters to display the desired character, and second actually pressing the button displaying the desired character. The two steps make the speed of the method slow compared with any of the others.